Stem cells spotlighted in Baxter heart study

Treatment believed to reverse heart failure

July 16, 2007|By Rob Waters, Bloomberg News

Delmar Chase, 74, has had two coronary bypass surgeries, stents inserted into his arteries to prop them open and a pacemaker to keep his heart beating normally. Still, he gets chest pain when he walks a block.

Relief may be on the way. Chase is enrolled in a Baxter International Inc. study, to be completed in 2009, testing if his own stem cells can strengthen his heart. The trial is one of 50 involving 3,200 patients worldwide conducted by academic researchers and a dozen companies racing to market new treatments for heart disease, the No. 1 U.S. killer.

In March, Osiris Therapeutics Inc. and Mytogen Inc. showed in separate studies that stem cells improved the pumping of diseased hearts. Two weeks ago, Deerfield-based Baxter said a similar therapy decreased chest pain in two dozen people. Further reports may signal whether these therapies will crack the $33 billion-a-year U.S. cardiac-care market.

"There's a lot of money to chase and a lot of companies want a piece," said Jose Haresco, an analyst with Merriman Curhan Ford & Co. in San Francisco. "Cardiology is the largest area of health expenditures in the country."

Most heart therapies prevent cardiovascular damage by lowering blood pressure or cholesterol. No existing treatment actually reverses heart failure, which weakens cardiac muscle and often follows a heart attack. More than 5 million Americans have the disorder, according to the American Heart Association.

The new experiments all use adult stem cells harvested from blood, bone, muscle and fat. In most studies they are gathered from a patient's own organs, purified in the laboratory, then injected back into an individual's heart.

In March, Mytogen, based in Phoenix, said it used such a technique to treat 12 heart failure patients, whose hearts pumped more efficiently six months later. In May, Advanced Cell Technology Inc., an embryonic stem cell company based in Alameda, Calif., agreed to acquire Mytogen for $5 million and assume $1 million in debt.

Osiris, based in Baltimore, is developing a treatment using cells gathered from unrelated donors and injected into patients' veins that may be easier for hospitals to use.

Up to 5,000 treatments can be made from one donor. "The cells can be produced in quantity, in advance, offering the chance for an off-the-shelf product," said Marc Penn, director of the Bakken Heart-Brain Institute at the Cleveland Clinic.

The Osiris procedure reduced risks of irregular heartbeats in patients given the cells within 10 days of a heart attack, compared with patients on placebos, the study found.

Though some researchers say stem cells from embryos may be more effective in rebuilding hearts, all American trials use the less controversial adult cells. The U.S. government severely limits funding for embryonic stem cell research.

Kenneth Chien, a Harvard University researcher, said human studies should be put on hold until scientists better understand how stem cells work. He also said the focus of research should shift to more adaptable embryonic cells. Last year, Chien published research identifying a "master" cardiac cell, derived from an embryonic cell, that turns into each of the three major cell types found in the heart.

He said scientists should carry out more studies in test tubes and animals before moving to people.

"What's the best way to deliver cells?" Chien asks. "Injection into the heart, in the bloodstream? Which cells? Bone marrow? Fat cells? We don't really know."

Answering such questions is the point of early studies, said Stephen Minger, director of the stem cell biology laboratory at King's College in London. Adult stem cells may serve as a bridge until researchers better understand how embryonic cells work, he said.

Minger thinks bone marrow cells may help form new blood vessels, which the damaged heart needs, and that the ultimate treatment may combine adult cells to stimulate blood flow and embryonic cells to form new muscle.

Delmar Chase hopes cells from his bone marrow will strengthen his heart, though he won't learn until 2009 if he was given the cells or a placebo.

He was treated in February at the Scripps Institute's Green Hospital in La Jolla, Calif. During the operation, cardiologist Richard Schatz, 54, peered intently at six monitors with images of Chase's heart from a camera on a catheter, a hollow wire threaded into an artery.

Guided by the images, Schatz's team manipulated the catheter to areas of the heart getting too little blood and oxygen. Then, using a syringe, they plunged a needle into the heart's wall, discharging either cells or saline.

Baxter plans to treat the last of 150 patients in the study by March next year, follow them for a year, then decide whether to finance a larger trial, said Andrea Hunt, the company's vice president for cellular therapies.

Chase believes the Baxter study is already a success, at least for him. He has needed just one nitroglycerine tablet a week since three weeks after the operation occurred. Before, he was averaging four a day, he said. For that reason, he assumes he got stem cells, not saline.

"I'm pretty sure we're on the right road," Chase said. "It's the best news I've had in 35 years."